EPA Releases Final SACC Report on Draft D4 Risk Evaluation, Reaffirming Commitment to Gold Standard Science and to Inform the Strongest Possible Protections

Released June 12, 2026

Today, the U.S. Environmental Protection Agency (EPA) released the Science Advisory Committee on Chemicals (SACC) final report and meeting minutes from the December 2–4, 2025, virtual public meeting on the draft risk evaluation for octamethylcyclotetrasiloxane (D4) under the Toxic Substances Control Act (TSCA). D4 is used to make silicone polymers and is found in everyday products like cosmetics and hair care — which is precisely why EPA is committed to getting this evaluation right and using it to support the most protective measures the science supports, consistent with TSCA’s requirements.

Independent peer review is an integral step in ensuring EPA's chemical reviews meet the highest scientific standard and gives the agency confidence in the data and methods used to evaluate a chemical's risks. The SACC peer-reviewed the draft risk evaluation and technical support documents for D4 in December 2025 and identified opportunities to make the evaluation more complete. EPA welcomes this input and will use the SACC's comments, together with public comments, to strengthen the final TSCA risk evaluation for D4.

Consistent with this Administration's commitment to radical transparency, the final report and meeting minutes are available in docket EPA-HQ-OPPT-2025-1610 on www.regulations.gov and through the SACC webpage, Peer Review of the Draft Risk Evaluation for D4.

The SACC serves as the primary scientific peer-review mechanism for EPA's Office of Chemical Safety and Pollution Prevention, providing independent scientific advice and recommendations on the scientific basis for risk assessments, methodologies, and pollution prevention approaches for chemicals regulated under TSCA.

For additional information, contact the Designated Federal Official, Dr. Alaa Kamel, at kamel.alaa@epa.gov.